In the field of semiconductor processing, a number of techniques have been described to convert thin amorphous silicon films into polycrystalline films. For example, in James Im et al., “Crystalline Si Films for Integrated Active-Matrix Liquid-Crystal Displays,” 11 MRS Bulletin 39 (1996), an overview of conventional excimer laser annealing technology is described. In such conventional system, an excimer laser beam is shaped into a beam having an elongated cross-section which is typically up to 30 cm long and 500 micrometers or greater in width. The shaped beam is stepped over a sample of amorphous silicon (i.e., by translating the sample) to facilitate melting thereof and to effectuate the formation of grain-shape and grain boundary-controlled polycrystalline silicon upon the re-solidification of the sample. Such techniques has been referred to as sequential lateral solidification (“SLS”) of the melted portions of the sample to effectuate the growth of longer grain boundaries therein so as to achieve, e.g., uniformity among other thing.
Various techniques, processes, masks and samples have been previously described which utilize various SLS techniques, to effectively process the sample. For example, International Publication No. 02/086954 describes a method and system for providing a single-scan, continuous motion sequential lateral solidification of melted sections of the sample being irradiated by beam pulses. In this publication, an accelerated sequential lateral solidification of the polycrystalline thin film semiconductors provided on a simple and continuous motion translation of the semiconductor film are achieved, without the necessity of “microtranslating” the thin film, and re-irradiating the previously irradiated region in the direction which is the same as the direction of the initial irradiation of the thin film while the sample is being continuously translated.
One problem that may arise during SLS processing of a thin film provided on a sample is microstructural artifacts, e.g., grain misalignment. For example, these artifacts may be formed in the area of beamlet overlap. Such areas in which artifacts may form may be tail areas of the newest beamlet(s) irradiating the sample which overlap front or head areas of the previously irradiated and resolidified portion of the sample. These artifacts may arise because the edge of the beam (e.g., rounded or square-shaped), which is reproduced in the molten portion, leads to lateral growth of grains extending in from the edges at angles that are skewed to the desired direction of the lateral growth.